This invention relates to derivatives of rapamycin which are useful as immunogenic molecules for the generation of antibodies specific for rapamycin or ring opened derivatives thereof, for measuring levels of rapamycin or derivatives thereof; for isolating rapamycin binding proteins; and detecting antibodies specific for rapamycin or derivatives thereof.
Rapamycin is a macrocyclic triene antibiotic produced by Streptomyces hygroscopicus which was found to have antifungal activity, particularly against Candida albicans, both in vitro and in vivo [C. Vezina et al., J. Antibiot. 28, 721 (1975); S. N. Sehgal et al., J. Antibiot. 28, 727 (1975); H. A. Baker et al., J. Antibiot. 31, 539 (1978); U.S. Pat. No. 3,929,992; and U.S. Pat. No. 3,993,749].
Rapamycin alone (U.S. Pat. No. 4,885,171) or in combination with picibanil (U.S. Pat. No. 4,401,653) has been shown to have antitumor activity. R. Martel et al. [Can. J. Physiol. Pharmacol. 55, 48 (1977)] disclosed that rapamycin is effective in the experimental allergic encephalomyelitis model, a model for multiple sclerosis; in the adjuvant arthritis model, a model for rheumatoid arthritis; and effectively inhibited the formation of IgE-like antibodies.
The inmunosuppressive effects of rapamycin have been disclosed in FASEB 3, 3411 (1989). Cyclosporin A and FK-506, other macrocyclic molecules, also have been shown to be effective as immunosuppressive agents, therefore useful in preventing transplant rejection [FASEB 3, 3411 (1989); FASEB 3, 5256 (1989); R Y. Calne et al., Lancet 1183 (1978); and U.S. Pat. No. 5,100,899].
Rapamycin has also been shown to be useful in preventing or treating systemic lupus erythematosus [U.S. Pat. No. 5,078,999], pulmonary inflammation [U.S. Pat. No. 5,080,899], insulin dependent diabetes mellitus [Fifth Int. Conf. Inflamm. Res. Assoc. 121 (Abstract), (1990)], adult T-cell leukemia/lymphoma [European Patent Application 525,960 A1, and smooth muscle cell proliferation and intimal thickening following vascular injury [Morris, R. J. Heart Lung Transplant 11 (pt. 2): 197 (1992)].
Mono- and diacylated derivatives of rapamycin (esterified at the 28 and 43 positions) have been shown to be useful as antifungal agents (U.S. Pat. No. 4,316,885) and used to make water soluble prodrugs of rapamycin (U.S. Pat. No. 4,650,803). Recently, the numbering convention for rapamycin has been changed; therefore according to Chemical Abstracts nomenclature, the esters described above would be at the 31- and 42-positions. U.S. Pat. No. 5,100,883 discloses fluorinated esters of rapamycin. U.S. Pat. No. 5,118,677 discloses amide esters of rapamycin. U.S. Pat. No. 5,118,678 discloses carbamates of rapamycin. U.S. Pat. No. 5,130,307 discloses aminoesters of rapamycin. U.S. Pat. No. 5,177,203 discloses sulfonates and sulfamates of rapamycin. U.S. Pat. No. 5,194,447 discloses sulfonylcarbamates of rapamycin. PCT Publication WO 92/05179 discloses carboxylic acid esters of rapamycin.
Yatscoff has reported that rapamycin levels can be quantitated using HPLC method with a sensitivity of 1 ng/ml [Ther. Drug Monitoring 14:138 (1992)] This method is time consuming and each sample must be assayed individually.
Immunoassays have been developed for numerous proteins as well as various drugs including cyclosporin A [Morris, R. G., Ther. Drug Monitoring 14:226-(1992)], and FK506 [Tamura, Transplant Proc. 19:23 (1987); Cadoff, Transplant Proc. 22:50 (1990)]. Numerous types of immunoassays, that have been developed to measure proteins or compounds, have been based on competitive inhibition, dual antibodies, receptor-antibody interactions, antigen capture, dipsticik, antibody or receptor trapping, or on affinity chromatography. Affinity columns with rapamycin have been reported in which a rapamycin analog was covalently attached to a matrix [Fretz J. Am. Chem. Soc. 113:1409 (1991)]. These columns have been used to isolate rapamycin binding proteins.
This invention provides a rapamycin conjugate of formula I, having the structure 
wherein R1 and R2 are each, independently, hydrogen or xe2x80x94(R3xe2x80x94Lxe2x80x94R4)axe2x80x94;
L is a linking group;
R3 is selected from the group consisting of carbonyl, xe2x80x94S(O)xe2x80x94, xe2x80x94(O)2, xe2x80x94P(O)2xe2x80x94, xe2x80x94P(O)(CH3)xe2x80x94, xe2x80x94C(S)xe2x80x94, and xe2x80x94CH2C(O)xe2x80x94;
R4 is a selected from the group consisting of carbonyl, xe2x80x94NHxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CH2xe2x80x94, and xe2x80x94Oxe2x80x94,
a=1-5;
x=0-1;
y=0-1;
z is from about 1 to about 120;
and Carrier is immunogenic carrier material, detector carrier material, or a solid matrix, or a salt thereof with the proviso that R1 and R2 are both not hydrogen; and further provided that when a is greater than 1, each L group can be the same or different, and still further provided that x is 0 if R1 is hydrogen and y is 0 if R2 is hydrogen, and if x and y are both 1, the Carrier moiety is the same in both cases.
The linking group, L, is any moiety that contains the group R3 on one end and R4 on other end, therefore enabling the linking group to be connected to the 42- and/or 31-hydroxyl groups of rapamycin on one end and connected to another linking group or the immunogenic carrier material, detector material, or matrix on the other end. When a is greater than 1, each L group can be the same or different. In such cases, the first L group is designated as L1, the second L group designated as L2 and so on. The rapamycin conjugates of the present invention may be prepared in such ways as to encompass a wide range of linking groups (L) and terminal functional groups R4. For example, L may be linear or branched alkylenes comprising from 1 to as many as 15, more usually 10 or less, and normally less than 6 carbon atoms (i.e., methylene, ethylene, n-propylene, iso-propylene, n-butylene, and so forth). In addition, such alkylenes can contain other substituent groups such as cyano, amino (including substituted amino), acylamino, halogen, thiol, hydroxyl, carbonyl groups, carboxyl (including substituted carboxyls such as esters, amides, and substituted amides). The linking group L can also contain or consist of substituted or unsubstituted aryl, aralkyl, or heteroaryl groups (e.g., phenylene, phenethylene, and so forth). Additionally, such linkages can contain one or more heteroatoms selected from nitrogen, sulfur and oxygen in the form of ether, ester, amido, amino, thio ether, amidino, sulfone, or sulfoxide. Also, such linkages can include unsaturated groupings such as olefinic or acetylenic bonds, disulfide, imino, or oximino groups. Preferably L will be a chain, usually aliphatic comprising between 1 and about 20 atoms, more usually between 1 and 10, excluding hydrogen, of which between 0 and 5 are heteroatoms preferrably selected from nitrogen, oxygen, and sulfur. Therefore, the choice of linking group L is not critical to the present invention and may be selected by one of ordinary skill taking normal precautions to assure that stable compounds are produced.
A preferred embodiment of this invention provides a conjugate of formula II, having the structure 
R1 and R2 are each, independently, hydrogen or xe2x80x94R3xe2x80x94Lxe2x80x94R4xe2x80x94;
L is xe2x80x94Axe2x80x94(CR5R6)b[Bxe2x80x94(CR7R8)d]exe2x80x94
A is xe2x80x94CH2xe2x80x94 or xe2x80x94NR9xe2x80x94;
B is xe2x80x94Oxe2x80x94, xe2x80x94NR9, xe2x80x94Sxe2x80x94, xe2x80x94S(O)xe2x80x94, or xe2x80x94S(O)2xe2x80x94;
R3 is selected from the group consisting of carbonyl, xe2x80x94S(O)xe2x80x94, xe2x80x94S(O)2, xe2x80x94P(O)2xe2x80x94, xe2x80x94P(O)(CH3)xe2x80x94, xe2x80x94C(S)xe2x80x94, and xe2x80x94CH2C(O)xe2x80x94;
R4 is selected from the group consisting of carbonyl, xe2x80x94NHxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CH2xe2x80x94, and xe2x80x94Oxe2x80x94;
R5, R6, R7, and R8 are each, independently, hydrogen, alkyl of 1-6 carbon atoms, alkenyl of 2-7 carbon atoms, alkynyl of 2-7 carbon atoms, halo, hydroxy, trifluoromethyl, arylalkyl of 7-10 carbon atoms, aminoalkyl of 1-6 carbon atoms, hydroxyalkyl of 1-4 carbon atoms, alkoxy of 1-6 carbon atoms, carbalkoxy of 2-7 carbon atoms, cyano, amino, xe2x80x94CO2H, or phenyl which is optionally mono-, di-, or tri-substituted with a substituent selected from alkyl of 1-6 carbon atoms, alkoxy of 1-6 carbon atoms, hydroxy, cyano, halo, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, amino, or xe2x80x94CO2H;
R9 is hydrogen, alkyl of 1-6 carbon atoms, or aralkyl of 7-10 carbon atoms;
b=0-10;
d=0-10;
e=0-2;
x=0-1;
y=0-1;
z is from about 1 to about 120;
and Carrier is immunogenic carrier material, detector carrier material, or a solid matrix, or a salt thereof with the proviso that R1 and R2 are both not hydrogen; and
further provided that when b is greater than 1, each of the CR5R6 groups can be the same or different, and when d is greater than 1, each of the CR7R8 groups can be the same or different; and still further provided that x is 0 if R1 is hydrogen and y is 0 if R2 is hydrogen, and if x and y are both 1, the Carrier moiety is the same in both cases.
A second preferred embodiment of this invention provides a conjugate of formula III, having the structure 
R1 and R2 are each, independently, hydrogen or xe2x80x94(R3xe2x80x94L1xe2x80x94R4)fxe2x80x94(R10xe2x80x94L2xe2x80x94R11)gxe2x80x94Carrier;
L1 is xe2x80x94(CH2)hxe2x80x94CHR12xe2x80x94(CH2)jxe2x80x94;
L2 is xe2x80x94(CH2)kxe2x80x94Dxe2x80x94(CH2)mxe2x80x94Exe2x80x94;
D is xe2x80x94CH2xe2x80x94, xe2x80x94Sxe2x80x94Sxe2x80x94, or 
E is xe2x80x94CH2xe2x80x94 or 
R3 and R10 are each, independently, selected from the group consisting of carbonyl, xe2x80x94S(O)xe2x80x94, xe2x80x94S(O)2, xe2x80x94P(O)2xe2x80x94, xe2x80x94P(O)(CH3)xe2x80x94, xe2x80x94C(S)xe2x80x94, and xe2x80x94CH2C(O)xe2x80x94;
R4 and R11 are each, independently, selected from the group consisting of carbonyl, xe2x80x94NHxe2x80x94, xe2x80x94Sxe2x80x94, 13 CH2xe2x80x94, and xe2x80x94Oxe2x80x94;
R12 is hydrogen, alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkenyl of 2-7 carbon atoms, alkynyl of 2-7 carbon atoms, xe2x80x94(CH2)nCO2R13, xe2x80x94(CH2)pNR14R15, carbamylalkyl of 2-3 carbon atoms, aminoalkyl of 1-4 carbon atoms, hydroxyalkyl of 1-4 carbon atoms, guanylalkyl of 2-4 carbon atoms, mercaptoalkyl of 1-4 carbon atoms, alkylthioalkyl of 2-6 carbon atoms, indolylmethyl, hydroxyphenylmethyl, imdazoylmethyl, halo, trifluoromethyl, or phenyl which is optionally mono-, di-, or tri-substituted with a substituent selected from alkyl of 1-6 carbon atoms, alkoxy of 1-6 carbon atoms, hydroxy, cyano, halo, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, amino, or xe2x80x94CO2H;
R14, and R15 are each, independently, hydrogen, alkyl of 1-6 carbon atoms, or arylalkyl of 7-10 carbon atoms;
R13 is hydrogen, alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkenyl of 2-7 carbon atoms, alkynyl of 2-7 carbon atoms, or phenyl which is optionally mono-, di-, or tri-substituted with a substituent selected from alkyl of 1-6 carbon atoms, alkoxy of 1-6 carbon atoms, hydroxy, cyano, halo, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, amino, or xe2x80x94CO2H;
f=0-3;
g=0-1;
h=0-10;
j=0-10;
k=0-10;
m=0-10;
n=0-6;
p=0-6;
x=0-1;
y=0-1;
z is from about 1 to about 120;
and Carrier is immunogenic carrier material, detector carrier material, or a solid matrix, or a salt thereof with the proviso that R1 and R2 are both not hydrogen; and further provided that f and g are both not 0 and when f is greater than 1, each of the xe2x80x94(R3xe2x80x94L1xe2x80x94R4)xe2x80x94moieties can be the same or different; and still further provided that x is 0 if R1 is hydrogen and y is 0 if R2 is hydrogen, and if x and y are both 1, the Carrier moiety is the same in both cases.
This invention also provides a conjugate of formula IV, having the structure 
wherein R1 is xe2x80x94OCH2(CH2)qR4xe2x80x94;
R4 is selected from the group consisting of carbonyl, xe2x80x94NHxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94CH2xe2x80x94, and xe2x80x94Oxe2x80x94;
q=0-6;
z is from about 1 to about 120;
and Carrier is immunogenic carrier material, detector carrier material, or a solid matrix, or a salt thereof.
The immunogenic carrier material can be selected from any of those conventionally known. In most cases, the carrier will be a protein or polypeptide, although other materials such as carbohydrates, polysaccharides, lipopolysaccharides, nucleic acids and the like of sufficient size and immunogenicity can likewise be used. For the most part, immunogenic proteins and polypeptides will have molecular weights between 5,000 and 10,000,000, preferably greater than 15,000 and more usually greater than 40,000. Generally, proteins taken from one animal species will be immunogenic when introduced into the blood stream of another species. Particularly useful proteins are those such as albumins, globulins, enzymes, hemocyanins, glutelins or proteins having significant non-proteinaceous constituents, e.g., glycoproteins, and the like. Further reference for the state-of-the-art concerning conventional immunogenic carrier materials and techniques for coupling haptens thereto may be had to the following: Parker, Radioimmunoassay of Biologically Active Compounds, Prentice-Hall (Englewood Cliffs, N.J., USA, 1976), Butler, J. Immunol. Meth. 7:1-24 (1975) and Pharmacol. Rev. 29(2):103-163 (1978); Weinryb and Shroff, Drug Metab. Rev. 10:P271-283 (1975); Broughton and Strong, Clin. Chem. 22:726-732 (1976); and Playfair et al., Br. Med. Bull. 30:24-31 (1974). Preferred immunogenic carrier materials for use in the present invention are ovalbumin and keyhole limpet hemocyanin. Particularly preferred for use in the present invention is ovalbumin. The detector carrier material can be a rapamycin-linking moiety conjugated to an enzyme such as horseradish peroxidase, alkaline phosphatase, luciferase, a fluorescent moiety such as fluorescein or fluorescein derivatives, Texas Red, or rhodamine, a chemiluminescent moiety, and the like. The solid matrix carrier material can be resin beads, an ELISA plate, glass beads as commonly used in a radioimmunoassay, plastic beads, solid matrix material typically used in a dipstick-type assay. When rapamycin is conjugated to a solid matrix, the resulting conjugate can be used in a dipstick assay, as described in this disclosure, for the affinity purification of antibodies, or for isolating rapamycin binding proteins.
It should be noted that as used in the formulae above describing the specific rapamycin conjugates, z represents the number of rapamycin conjugated to the carrier material. The value z is sometimes referred to as the epitopic density of the immunogen, detector, or solid matrix and in the usual situation will be on the average from about 1 to about 120 and more typically from 1 to 50. The densities, however, may vary greatly depending on the particular carrier material used.
When any of the compounds of this invention contain an aryl or arylalkyl moiety, it is preferred that the aryl portion is a phenyl, naphthyl, pyridyl, quinolyl, isoquinolyl, quinoxalyl, thienyl, thionaphthyl, furyl, benzofuryl, benzodioxyl, benzoxazolyl, benzoisoxazolyl, or benzodioxolyl group that may be optionally mono-, di-, or tri-substituted with a group selected from alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkoxy of 1-6 carbon atoms, cyano, halo, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, amino, dialkylamino of 1-6 carbon atoms per alkyl group, alkylthio of 1-6 carbon atoms, xe2x80x94SO3H and xe2x80x94CO2H. It is more preferred that the aryl moiety is a phenyl group that is optionally mono-, di-, or tri-substituted with a group selected from alkyl of 1-6 carbon atoms, arylalkyl of 7-10 carbon atoms, alkoxy of 1-6 carbon atoms, cyano, halo, nitro, carbalkoxy of 2-7 carbon atoms, trifluoromethyl, amino, dialkylamino of 1-6 carbon atoms per alkyl group, alkylthio of 1-6 carbon atoms, xe2x80x94SO3H and xe2x80x94CO2H.
The salts, are those derived from such inorganic cations such as sodium, potassium, and the like; organic bases such as: mono-, di-, and trialkyl amines of 1-6 carbon atoms, per alkyl group and mono-, di-, and trihydroxyalkyl amines of 1-6 carbon atoms per alkyl group, and the like; and organic and inorganic acids as: acetic, lactic, citric, tartaric, succinic, maleic, malonic, gluconic, hydrochloric, hydrobromic, phosphoric, nitric, sulfuric, methanesulfonic, and similarly known acceptable acids.
The compounds of this invention can be prepared by reacting the 42- and/or 31-hydroxyl groups of rapamycin with a suitable electrophilic reagent that will serve as the linker moiety. The following patents exemplify the preparation of the 42- and/or 31-derivatives of rapamycin that can be used as linking groups for the preparation of the compounds of this invention. The preparation of fluorinated esters of rapamycin is described in U.S. Pat. No. 5,100,883. The preparation of amide esters is disclosed in U.S. Pat. No. 5,118,677. The preparation of carbamates of rapamycin is disclosed in U.S. Pat. No. 5,118,678. The preparation of aminoesters of rapamycin is described in U.S. Pat. 5,130,307. The preparation of sulfonates and sulfamates of rapamycin are described in U.S. Pat. No. 5,177,203. The preparation of sulfonylcarbamates of rapamycin are described in U.S. Pat. No. 5,194,447. The disclosures of the above cited U.S. patent are hereby incorporated by reference. From these patents, it can be seen that reactive electrophiles such as isocyanates, used in the preparation of carbamates, or sulfonyl chlorides, used in the preparation of sulfonates, can be reacted with the hydroxyl groups of rapamycin without the need for an activating agent. For the esterification of the rapamycin hydroxyl groups with a carboxylic acid, activation is usually required through the use of a coupling reagent such as DCC, or a water soluble analog thereof, such as dimethylaminopropyl)-3-ethyl carbodiimide (DAEC). Representative examples of the preparation of rapamycin-linking group moieties are provided as examples below. The preparation of ether derivatives of rapamycin can be accomplished using the methodology disclosed in Example 18.
For the compounds of this invention in which the linker group is attached to the 42- or the 31,42-hydroxyls, the electrophile (or activated electrophile) is reacted with rapamycin to typically provide a mixture of the 42- and 31,42-derivatized rapamycin that can be separated by chromatography. For the compounds of this invention in which the linker group is attached to the 31-hydroxyl of rapamycin, the 42-hydroxyl group must be protected with a suitable protecting group, such: as with a tert-butyldimethyl silyl group. The 31-hydroxyl can then be reacted with a suitable electrophile to provide the derivatzed rapamycin, followed by deprotection of the 42-hydroxyl group. The preparation of 42-O-silyl ethers of rapamycin and subsequent deprotection is described in U.S. Pat. No. 5,120,842, which is hereby incorporated by reference. Preparation of compounds containing different linkers at the 31- and 42-positions can be accomplished by first preparing the 42-derivatized compound and then using a different linker to derivatize the 31-position. The preparation of the 27-oxime linking groups can be accomplished using the methodology disclosed in U.S. Pat. No. 5,023,264, which is hereby incorporated by reference; and as described in Example 21.
The linker group attached to rapamycin can be coupled to a second linker group using standard methodology described in the peptide literature; typically by activating the electrophilic moiety, with DCC type coupling reagent, or with N-hydroxysuccinimide, or as an activated ester or anhydride. The activated electrophilic end of one linking moiety can then be reacted with the nucleophilic end of the other linker moiety.
The coupling of the rapamycin linking group moiety to the immunogenic carrier can be accomplished under standard literature conditions. In general, for reaction with a nucleophilic group on the immunogenic carrier material, an electrophilic moiety, such as a carboxylic acid, on the linking group is activated with a suitable activating agent such as N-hydroxysuccinimide, and then reacted with the nueleophilic moiety on the immunogenic carrier material. Examples 2 and 3 specifically exemplify this technique. Similar methodology is employed for the coupling of a nucleophilic moiety on the linking group to an electrophilic moiety on the immunogenic carrier material. In such cases, the electrophilic moiety on the immunogenic carrier material is activated as described above, and then reacted with the nucleophilic end of the linking group.
The reagents used to prepare the compounds of the invention are commercially available or can be prepared by methods that are disclosed in the literature.
This invention also covers analogous conjugates of other rapamycins such as, but not limited to, 29-demethoxyrapamycin, [U.S. Pat. No. 4,375,464, 32-demethoxyrapamycin under C.A. nomenclature]; rapamycin derivatives in which the double bonds in the 1-, 3-, and/or 5-positions have been reduced [U.S. Pat. No. 5,023,262]; 42-oxorapamycin [U.S. Pat. No. 5,023,2621; 27-oximes of rapamycin [U.S. Pat. No. 5,023,264]; 27-hydrazones of rapamycin [U.S. Pat. No. 5,120,726]; 29-desmethylrapamycin [U.S. Pat. No. 5,093,339, 32-desmethyirapamycin under C.A. nomenclature]; 7, 29-bisdesmethylrapamycin [U.S. Pat. No. 5,093,338, 7, 32-desmethylrapamycin under C.A. nomenclature]; and 15-hydroxy- and 15,27-bishydroxy-rapamycin [U.S. Pat. No. 5,102,876]. The disclosures in the above cited U.S. patents are hereby incorporated by reference. Also covered are conjugates of the rapamycin 1,3-Diels Alder adduct with diethyl azidodicarboxylate and rapamycin 1,3-Diels Alder adduct with phenyltriazoline dione. The preparation of these compounds is described in Examples 14 and 15.
The compounds of this invention are rapamycin immunogen, detector, and matrix bound conjugates that are useful for the generation and detection of antibodies specific for rapamycin and derivatives thereof, for measuring levels of rapamycin or a derivative thereof in biological or laboratory fluids, and for isolating rapamycin binding proteins. Rapamycin derivatives as defined here are compounds containing a rapamycin nucleus, a metabolite of rapamycin, or a ring opened rapamycin (such as secorapamycin, described in U. S. Pat. No. 5,252,579, which is hereby incorporated by reference), in which one or more of the hydroxyl groups has been esterified into a carboxylic ester, a carbamate, a sulfonate ester, an amide, or the like, or one or more of the ketones has been reduced to a hydroxyl group, or one or more of the double bonds has been reduced, or one ketones has been converted to an oxime or a hydrazone. Other rapamycin derivatives for which the compounds of this invention can be used for measuring levels of or generating antibodies to will be apparent to one skilled in the art based on this disclosure.
Antibodies specific for rapamycin or a derivative thereof using the rapamycin immunogen conjugates of this invention may be generated by standard techniques that are known in the art. Typically, a host animal is inoculated at one or more sites with the immunogen conjugate, either alone or in combination with an adjuvant. The typical host mammals include, but are not limited to, mice, goats, rabbits, guinea pigs, sheep, or horses. Subsequent injections can be made until a sufficient titer of antibodies are produced. The antibodies generated from the rapamycin immunogen conjugates of this invention can be used in numerous immunoassays, for determining rapamycin levels, in ELISAs, radioimmunoassays, in chemiluminesence immunoassays, and in fluorescent immunoassays. Although many variations of the immunoassay can be used (antigen capture, antibody capture, competitive inhibition, or two antibody immunoassay), a basic competitive inhibition immunoassay can be performed as follows: Antibody specific for the ligand is usually bound to a matrix. A solution is applied to decrease nonspecific binding of the ligand to the matrix. After rinsing the excess away, the antibody coupled matrix may be treated in some cases so it can be stored. In a competitive inhibition assay, the ligand standard curve is made and added with the rapamycin detector conjugate to compete for binding to the rapamycin-specific antibody. If necessary, the excess is removed. The detector molecule is detected by the standard methods used by one skilled in the art. Different formats can be used, which include but are not limited to, dipstick assays, FPIA, EMIT, ELISA, VISTA, RIA, and MEIA. Detector conjugates of the present invention can-be prepared to use in the above assays. For example, the detector conjugates can be Carrier material with labeled fluorescent, chemiluminescent, or enzymatic moieties.
This invention also provides for the use of the rapamycin immunogen conjugates or antibodies specific for rapamycin or a derivative thereof in a test kit that can be commercially marketed. The test kit may be used for measuring levels of rapamycin in biological or laboratory fluids. Test kit components may include antibodies to rapamycin or a derivative thereof, antisera, or rapamycin carrier conjugates. The conjugates or antibodies may be bound to a solid matrix, and rapamycin derivatives or antibodies may be radiolabeled if the assay so requires. Standard concentrations of rapamycin can be included so that a standard concentration curve can be generated. Suitable containers, microtiter plates, solid supports, test tubes, trays, can also be included in any such kit. Many variations of reagents can be included in the kit depending on the type of assay used.
The following is illustrative of the use of a rapamycin immunogen conjugate of this invention to generate antibodies specific for rapamycin or a derivative thereof and detect them using an ELISA format immunoassay. Five mice were immunized with 50 xcexcg rapamycin 31,42-diester with glutaric acid conjugate with keyhole limpet hemocyanin in Complete Freund""s Adjuvant intrasplenically and after about one month were boosted with 50 xcexcg of rapamycin 31,42-diester with glutaric acid conjugate with keyhole limpet hemocyanin in incomplete Freund""s Adjuvant into the footpads. Microtiter plates (IMMUNOLON I) were coated overnight with 100 xcexcl of goat anti-mouse antibody (10 xcexcg/ml in 10 mM potassium phosphate buffer, pH 7.2) at 4xc2x0 C. The plates were flicked and blocked with 100 xcexcl of 1% bovine sera albumin in phosphate buffered saline overnight at 4xc2x0 C. After flicking and washing the plates thrice with 10 mM phosphate buffer, pH 7.05, 30 mM NaCl, 0.02% TRITON X-100 (polyethylene glycol tert-octylphenyl ether) and 0.004% thimerosal wash buffer, 100 xcexcl of each mouse sera diluted with phosphate buffer solution was added to a well and incubated at room temperature for overnight. After flicking and washing the plates thrice with wash buffer, rapamycin 31,42-diester with glutaric acid conjugate with horseradish peroxidase (compound of Example 10 (100 xcexcl, 0.5 ng/ml) was added and incubated for 1 hour at room temperature in the dark. After flicking and washing the plates thrice with wash buffer, tetramethyl benzidine (TMB) substrate with H2O2 was added and the plates were incubated covered for 30 min. at room temperature in the dark. The optical density was read on a spectrophotometer at 450 nm. As shown in Table I, five of the five mice had antibodies reactive for rapamycin 31,42diester with glutaric acid conjugate with horseradish peroxidase (compound of Example 10).
The results in Table 1 show that mouse 6904 produced the most antibodies to the compound of Example 10. Hybridomas were generated using standard methodology. Following a splenectomy of a mouse immunized and boosted 3 times with the compound of Example 4, spleen cells were fused to SP20 cells to produce hybridomas. The hybridomas were evaluated for the production of antibodies specific for rapamycin or a derivative thereof using an ELISA assay as briefly described below.
Microtiter plates (IMMUNOLON I) were coated overnight with 100 xcexcl of goat anti-mouse antibody (10 xcexcg/ml in 10 mM potassium phosphate buffer, pH 7.2) at 4xc2x0 C. The plates were flicked and blocked with 100 xcexcl of 1% bovine sera albumin in phosphate buffered saline (PBS) overnight at 4xc2x0 C. After flicking and washing the plates thrice with 0.2xc3x97PBS containing 0.02% TRITON X-100 and 0.004% thimerosal, 100 xcexcl of each hybridoma supernatant was added to a well and incubated at room temperature for overnight. After flicking and washing the plates thrice with 0.2xc3x97PBS containing 0.02% TRITON X-100 and 0.004% thimerosal, the compound of Example 22 (100 xcexcl, 0.17 xcexcM) was added and incubated for 1 hour at 4xc2x0 C. After flicking and washing the plates thrice with 0.2xc3x97PBS containing 0.02% TRITON X-100 and 0.004% thimerosal, strepavidin or avidin conjugated to horseradish peroxidase (100 xcexcl, 0.2 xcexcg/ml) was added and incubated at room temperature for 1 hour in the dark. After flicking and washing the plates thrice with 0.2xc3x97PBS containing 0.02% TRITON X-100 and 0.004% thimermsol, TMB substrate and H2O2 was added and the plates were incubated covered for 30 min. at room temperature in the dark. The optical density was read on a spectrophotometer at 450 nm. An optical density reading of 0.25-3 indicates specific antibody binding. The results in Table 2 show that the hybridoma from well P4G1 is positive for binding to the compound of Example 22, and is therefore specific for rapamycin or a derivative thereof.
The hybridoma cell line in P4G1 was cloned by limiting dilution and is designated as hybridoma cell line, RAP-42-OVAF2#1hc. In a Fluorescent Polarization Immunoassay (PPIA), rapamycin 42-ester with succinic acid conjugate with 5-glycinylfluoresceinamine (Example 23a) was used as a tracer at a concentration of 10 nM and showed a polarization of 77 mP in 100 mM sodium phosphate pH 7.5. After addition of an excess of FKBP12, the polarization measured 195 mP whereas the addition of excess of RAP-42-OVAF2#1 MoAb yielded 84 mP. The ring opened non-enzymatically transformed product of the above tracer (secorapamycin 42-ester with succinic acid conjugate with 5-glycinylfluoresceinamine; Example 24) was isolated on TLC plate (50 chloroform:4 methanol:0.5 acetic acid; migrated slowest of three components).
The rapamycin- and secorapamycin-fluorescein derivatives of Examples 23 and 24 were characterized by demonstrating their binding to FKBP12 and RAP-42-OVAF2#1 MoAb. On addition of 0.ug FKBP12 to 1.00 mL 10 nM rapamycin-fluorescein the fluorescence polarization increased from 57 mP to 148 mP, while the fluorescence polarization of the secorapamycin-fluorescein derivative increased from 49 mP only to 58 mP, indicating much weaker binding of the seco derivative. On addition of 5 ug/mL RAP-42-OVAF2#1 MoAb to the rapamycin derivative the fluorescence polarization was unchanged at 58 mP, while the secorapamycin derivative fluorescence polarization increased from 44 mP to 136 mP. This shows that RAP-42-OVAF2#1 MoAb binds specifically to the secorapamycin-fluorescein derivative, but not to its rapamycin-fluorescein precursor.
Specificity of the two systems was also demonstrated in an assay format. To 500 xcexcL 10 xcexcg/mL RAP-42-OVAF2#1 was added rapamycin or secorapamycin to give final concentrations ranging from 0 to 100 nM. Addition of 500 xcexcL 20 nM secorapamycin-fluorescein resulted in a fluorescence polarization of 124 mP in the absence of analyte, 120 mP in the presence of 100 nM rapamycin, and 74 mP in the presence of 100 nM secorapamycin. Secorapamycin analyte thus inhibits binding of the secorapamycin fluorescein derivative to RAP-42-OVAF2#1, while rapamycin has no effect. In the converse experiment, to 500 uL 0.02 ug/mL FKBP12 was added rapamycin or secorapamycin to give final concentrations ranging from 0 to 100 nM. Addition of 500 xcexcL 20 nM rapamycin-fluorescein resulted in a fluorescence polarization of 128 mP in the absence of analyte, 61 mP in the presence of 100 nM rapamycin, and 122 mP in the presence of 100 nM secorapamycin. Here rapamycin inhibited binding while secorapamycin has no effect.
A second antibody designated 34-294-163MoAb, that is specific for rapamycin was prepared as follows. A female, 6-8 week old, RBF/DnJ mouse (Jackson Laboratories, Bar Harbor, Me.) was immunized with rapamycin conjugated at the 42 position to bovine serum albumin with a hemisuccinate linker (designated as RAPA-42-HS-BSA) which was emulsified in Freund""s Adjuvant (Difco, Detroit, Mich.). The primary immunization was administered with Freund""s Complete Adjuvant and subsequent boosts with Freund""s Incomplete Adjuvant. The animal boosting interval for this long term immunized animal was at weeks 1, 3, 9, and 19, with the respective dosage level at 50, 25, 25, and 100 xcexcg per animal at two subcutaneous locations each time. The animal was allowed a 14 week rest period before a 5 xcexcg prefusion boost was administered to the spleen 3 days prior to fusion.
On the day of the fusion, the mouse was euthanized by a quick cervical dislocation and the spleen was removed. The, splenocytes are washed one time in Iscove""s Modified Dulbecco""s Medium (IMDM) (GIBCO, Grand Island, N.Y.) and centrifuged 1000 RPM for 10 minutes. The pelleted splenocytes are combined with SP2/0 myeloma cells (Dr. Milstein, Cambridge, United Kingdom) at a 1:1 ratio, washed in IMDM, and centrifuged; The supernatant was removed and 1 ml of 50% polyethylene glycol (PEG) (American Type Culture Collection, Manassas, Va.) was added to the pellet for 1 minute as the pellet was gently being dispersed by tapping and swirling. Thirty mLs of IMDM was added to the mixture and centrifuged as previously described. Supernate was decanted, the pellet was resuspended in IMDM with hypoxanthine, aminopterin, thymidine (HAT) (GIBCO) and 10% Fetal Bovine Serum (FBS) (Hyclone Laboratories, Logan, Utah). To enhance fusion frequency, 0.5% Salmonella typhimurium mitogen v/v (STM; RIBI Immunochem Research, Inc., Hamilton, Mont.) and 1% v/v ORIGEN (Igen, Rockville, Md.) were added to the fusion cell suspension plated into 96-well tissue culture plates.
The primary screening of the fusion occured on day 10 confluent cultures. An EIA was used to detect anti-rapamycin reactivity in the supernate samples. Microtiter wells were coated with 100 xcexcl of a 2 xcexcg/ml solution of 42-HS-BSA in phosphate buffered saline (PBS) and incubated at room temperature for 2 hours. The plates were blocked for 1 hour with 200 xcexcl per well of 3% bovine serum albumin (BSA) in PBS. After washing the plates 3 times with distilled water, 100 xcexcl of culture supernate was added per well and incubated 30 minutes. The plates were washed 3 times and 100 xcexcl per well of goat anti-mouse lgG+M-HRPO conjugate (Kirkegaard Perry Laboratories, Gaithersburg, Md.) diluted in the block solution was added to the plate for a 30 minute incubation period. The plate was washed a final time and the color development utilizes O-phenylenediamine: 2HCl (OPD) (Abbott Laboratories, Abbott Park, Ill.). The relative intensity of optical density readings identified hybrid 34-294 at least 5 times that of the negative control, normal mouse serum (NMS) (Organon Teknika-Cappel, Malvern, Pa.) and the hybrid was selected as a candidate for cloning and further evaluation.
Hybrid #34-294 was cloned by limiting dilutions from 1-100 to 1-1,0,000. The cloning media used was IMDM with 10% v/v FBS and 1% v/v HT Supplement (GIBCO). A 200 xcexcl cell suspension was added to each 96 well in the tissue culture plate.
Clone #34-294-163 (designated as 34294-163hc) was selected for further evaluation based on additional EIA screening of the clone supernate of confluent cultures. The EIA screening protocol used was described previously.
The Isotype of the monoclonal antibody secreted from the cell lines identified as 34-294-163 (designated as 34-294-163MoAb) was determined on a Mouse monoclonal antibody isotyping kit, RPN 29, (Amersham Life Science, Arlington Heights, 11). The assay was performed according to the vendor recommendations and the results indicate an isotype of 1gG1, kappa light chain.
The compounds of Examples 12 and 13 can be used in an assay for the detection of polyclonal antibodies and monoclonal antibodies specific for rapamycin or a derivative thereof as described below.
Microtiter plates (IMMUNOLON I) were coated overnight with 100 xcexcl of goat anti-mouse antibody (10 xcexcg/ml in 10 mM potassium phosphate buffer, pH 7.2) at 4xc2x0 C. The plates were flicked and blocked with 100 xcexcl of 1% bovine sera albumin in phosphate buffered saline overnight at 4xc2x0 C. After flicking and washing the plates thrice with wash buffer, 100 xcexcl of rabbit sera diluted 1:5 in phosphate buffered saline was added to a well and incubated at room temperature for overnight After flicking and washing the plates thrice with wash buffer, rapamycin 42-ester with 3-[3-(4imino-butylthio)succinimidyl]phenacylglycine conjugate with horseradish peroxidase (compound of Example 12) (100 xcexcl, 0.5 ng/ml) or rapamycin 42 ester with (N-(3-carboxyphenyl)-3-thiosuccinimidyl)glycine conjugate with horseradish peroxidase (compound of Example 13) (100 xcexcl, 0.5 ng/ml) was added and incubated for 1 hour at room temperature in the dark. After flicking and washing the plates thrice with wash buffer, TMB substrate with H2O2 was added and the plates were incubated covered for 30 min. at room temperature in the dark. The optical density was read on a spectrophotometer at 450 nm. The results are shown in Table III.
The data in Table 3 show that the compounds of Examples 12 and 13 can be used to detect antibodies specific for rapamycin or a derivative thereof in a mammal, as seen in rabbit number 81.
The following is an example of the measurement of rapamycin concentrations using a competitive inhibition assay for rapamycin with an ELISA format using an antibody specific for rapamycin. Microtiter plates (IMMUNOLON I) were coated overnight with 100 xcexcl of goat anti-mouse antibody (10 xcexcg/ml in 10 mM potassium phosphate buffer, pH 7.2) at 4xc2x0 C. The plates were flicked and blocked with 100 xcexcl of 1% bovine sera albumin in phosphate buffered saline overnight at 4xc2x0 C. After flicking and washing the, plates thrice with wash buffer, the rapamycin specific antibody described above (100 xcexcl of 1 xcexcg/ml) was added to each well and incubated at room temperature for 1-4 hour. After flicking and washing the plates thrice with wash buffer, rapamycin 31,42-bis(hemiglutarate) conjugate with horseradish peroxidase (100 xcexcl, 0.5 ng/ml) was added and incubated for 1 hour at room temperature in the dark. After flicking and washing the plates thrice with wash buffer, TMB substrate was added and the plates were incubated covered for 5 min at room temperature in the dark. The optical density was read on a spectrophotometer at 450 nm. Results of the competition between rapamycin and rapamycin 31,42-diester with glutaric acid conjugate with horseradish peroxidase binding to mouse sera are shown in Table 4. From these results, a standard curve can be constructed and the concentration of rapamycin in a sample can be determined.
The compound of Example 11 (rapamycin 42-ester with N-[9H-fluoren-9-ylmethoxy)carbonyl]glycine) can be deprotected by the procedure used in Example 12 (to give rapamycin 42-ester with glycine) and conjugated to a solid matrix. It can bind antibodies specific for rapamycin or a derivative thereof as used in some dipstick immunoassay methods or to isolate rapamycein binding proteins. The following example illustrates that 803 resonance units (RU) of the compound of Example 11 can be immobilized on a solid matrix using the BIAcore""s standard protocol based on EDC and NHS used in a BIAcore. This matrix bound 1401 RU units of rapamycin specific antibody. The kinetics of association and dissociation were determined for each concentration of antibody tested (0.625, 1.25, 2.5, 5.0, 10.0 ug/ml). These data show that the compound of Example 11, even when bound to a matrix was accessible to binding by a ring opened rapamycin-specific antibody and the interaction could be characterized. Similar procedures can be used to bind a rapamycin-binding protein to deprotected rapamycin 42-ester with N-[9H-fluoren-9-ylmethoxy)carbonyl]glycine conjugated matrix. This matrix can also be used for the isolation of novel binding proteins, as practiced by one skilled in the art. Deprotected rapamycin 42-ester with N-[9H-fluoren-9-ylmethoxy)carbonyl]glycine can be used to isolate binding proteins of rapamycin-FKBP complex by one of the following methods. In one approach, tissue or cell lysates containing the appropriate protease inhibitors are incubated with FKBP which has been incubated with a deprotected-rapamycin 42-ester with N-[9fluoren-9-ylmethoxy)carbonyl]glycine conjugated matrix for a sufficient time to allow binding. Various buffers are used to rinse the proteins which are nonspecifically bound. Proteins are released by the addition of additional buffers which disrupt the bond between the rapamycin nucleus-FKBP and the binding proteins.
The hybridoma cell line, RAP-42-OVAF2#1hc, was deposited under the terms of the Budapest Treaty at the American Type Culture Collection (ATCC) of 10801 University Boulevard, Manassas, Va. 20110-2209, USA, on Mar. 10, 1994, and was granted accession number HB 11568.
The hybridoma cell line 34-294-163hc has also been deposited under the terms of the Budapest Treaty at the ATCC on Apr. 6, 1994, and was granted accession number HB 11606.
The following examples represent the preparation of representative compounds of this invention.